US6031629A - Picture quality stabilizer for a color laser printer - Google Patents

Picture quality stabilizer for a color laser printer Download PDF

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Publication number
US6031629A
US6031629A US09/003,597 US359798A US6031629A US 6031629 A US6031629 A US 6031629A US 359798 A US359798 A US 359798A US 6031629 A US6031629 A US 6031629A
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United States
Prior art keywords
gray level
color
humidity
temperature
value
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Expired - Lifetime
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US09/003,597
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English (en)
Inventor
Takeshi Shibuya
Tatsunari Satou
Taisaku Seino
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Ricoh Co Ltd
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Hitachi Ltd
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Assigned to HITACHI, LTD. reassignment HITACHI, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SATOU, TATSUNARI, SEINO, TAISAKU, SHIBUYA, TAKESHI
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Publication of US6031629A publication Critical patent/US6031629A/en
Assigned to RICOH PRINTING SYSTEMS, LTD. reassignment RICOH PRINTING SYSTEMS, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HITACHI, LTD.
Assigned to RICOH COMPANY, LTD. reassignment RICOH COMPANY, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: RICOH PRINTING SYSTEMS, LTD.
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/56—Processing of colour picture signals
    • H04N1/60—Colour correction or control
    • H04N1/6027—Correction or control of colour gradation or colour contrast
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/46—Colour picture communication systems
    • H04N1/56—Processing of colour picture signals
    • H04N1/60—Colour correction or control
    • H04N1/6083—Colour correction or control controlled by factors external to the apparatus
    • H04N1/6091—Colour correction or control controlled by factors external to the apparatus by environmental factors, e.g. temperature or humidity

Definitions

  • the present invention relates to a color laser printer, specifically to a color laser printer which makes it possible to stabilize the quality of an image in response to environmental changes.
  • a printer using an electro-photographic method forms an electrostatic latent image by scanning an electrically charged surface of a photosensitive body using a laser beam, and performs image development by neutralizing the electrostatic latent image using a toner charged with a charge of the opposite polarity.
  • the amount of charge toner particle changes due to the environmental conditions of temperature and humidity. For example, under conditions of high temperature and high humidity, the amount of charge per single toner particle becomes smaller, and under conditions of low temperature and low humidity, the amount of charge per single toner particle becomes larger.
  • Japanese Patent Application Laid-Open Number 07-128974 (1995) is controlling the development apparatus by using a toner density detector and a sensor for detecting temperature and humidity
  • Japanese Patent Application Laid-Open Number 6-64238 (1994) proposes a method for correcting the laser intensity and switching the gamma correction tables by using a density sensor mounted on the photosensitive body.
  • An object of the present invention is to provide a dynamic correction function for establishing a stable gray scale characteristic and color balance when the environmental conditions of temperature and humidity change during the operation of a color laser printer.
  • the above object is attained by using a sensor for measuring the environmental temperature and humidity, a gray scale correction means for correcting individually the gray level of each color of Cyan (C), Magenta (M), Yellow (Y) and Black (K), and a mixed color correction means for correcting the value of the gray level of the individual color already corrected with the gray level correction means and for modifying the internal parameters of the mixed color correction means in responsive to changes in the environmental temperature and humidity.
  • FIG. 1 is a schematic diagram of a data processing system of the present invention.
  • FIG. 2 is a characteristic diagram of reference temperature and humidity.
  • FIG. 3 is a graph which shows an example of the lightness gray level characteristic.
  • FIG. 1 shows a schematic diagram of the data processing system in accordance with the present invention.
  • the image data 1 supplied by the main computer for example, is decomposed by 4-color decomposing means 2 into point-ordered data represented by a combination of the values of gray levels of the individual colors, Cyan (C), Magenta (M), Yellow (Y) and Black (K).
  • the gray level value is an integer generally defined to be between 0 and 255.
  • the gray level value will be normalized with 255 so as to be between 0 and 1.
  • the whole black print image corresponds to the case wherein the gray level value is 1.
  • the individual gray level value of the colors (C, M, Y, K) is processed with the gray level correction generally designated "gamma correction" by using the gray level correction means 8.
  • the gray level value C for Cyan is corrected by the following formula (1), for example,
  • the upper-bound correction table 4 contains the gray level value when the saturation (or lightness) reaches and is maintained at a designated constant value as the gray level value increases with respect to the relation between the gray level and the saturation level.
  • the table interpolation means is applied to the gray level values of M, Y and K.
  • an upper-bound correction table 4 and a gamma correction table 5 are prepared for each individual color in this embodiment.
  • the gray level correction means 8 corrects the effect of the temperature and humidity on the individual gray scale characteristic of the single color, and the failure in the color balance caused by the effect of the temperature and humidity on the print characteristic with respect to the color superposition is corrected by the mixed color correction means 9 to be described below.
  • the mixed color correction means 9 uses a simple linear transformation, in which the coefficient a ij is defined by interpolating the values in the mixed color correction table 6 in response to the output from the temperature and humidity sensor 3.
  • the gray scale values (C", M", Y”, K") are stored in the buffer memory 10, and next, the values are supplied as video signals to the printer engine 12 by the video signal generation circuit 11 in the plane order, whereby the printed output is finally obtained.
  • the individual correction table is composed of correction values for the reference environment 13 shown in FIG. 2.
  • the reference environment 13 is so defined as to comprise a set of 9 combinations of the low temperature (t 0 ), the room temperature (t 1 ), the high temperature (t 2 ), and the low humidity (h 0 ), the room humidity (h 1 ), and the high humidity (h 2 ).
  • FIG. 3 An example of the lightness characteristic without correction measured for one environment of the reference environment 13 is shown in FIG. 3.
  • the parameters g in the upper-bound correction table 4 and the parameters g in the gamma correction table 5 are defined for the individual colors at the individual environments so that the error between the lightness characteristic shown in FIG. 3 and the model formula (2) shown below may be minimized. ##EQU1##
  • a reproduced color estimation function for interpolating and estimating the measured color value corresponding to an arbitrary combination of gray level values is formed.
  • this interpolation function for example, the following scheme based on linear interpolation can be considered.
  • the gray level values of the colors C, M, Y and K to be interpolated are designated c, m, y and k.
  • the gray level values of the measurement points with their gray level values closest to the individual gray level values, are c0, c1, m0, m1, y0, y1, k0and k1, in which c0 ⁇ c ⁇ c1, m0 ⁇ m ⁇ m1, y0 ⁇ y ⁇ y1, and k0 ⁇ k ⁇ k1, and supposing that the calorimetric system is L*ab of CIE, the following formulae (3), (4) and (5) can be defined. ##EQU2##
  • the mixed color correction for four colors (c, m, y, k) is considered in the above description. In the case where the effect of the Black color on the color balance can be neglected, it is normally sufficient to consider a mixed color correction only for three colors (c, m, y).
  • the table correction means 7 for the upper-bound correction table 4, the g correction table 5 and the mixed color correction table 6 for the individual conditions of the reference environment 13 obtained so far is performed with the double linear interpolation scheme defined by the following formula (6).
  • t i ⁇ t ⁇ t.sub.(i+1, h i ⁇ h ⁇ h.sub.(i+1, for (i, j 0, 1).
  • the value of g for the environment outside the region 14 is defined to be the interpolated value at the closest boundary 15.
  • the interpolation scheme for the correction coefficient for other g's and a ij 's can be established similarly.
  • the picture quality stabilizer for compensating for the changes in the gray level characteristic (g characteristic) and the color balance for the temperature and humidity environment can be obtained.
  • the gray level characteristic and the color balance for an arbitrary temperature and humidity environment can be compensated effectively.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Color, Gradation (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Color Electrophotography (AREA)
  • Color Image Communication Systems (AREA)
US09/003,597 1997-01-08 1998-01-07 Picture quality stabilizer for a color laser printer Expired - Lifetime US6031629A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP9-001143 1997-01-08
JP00114397A JP3580063B2 (ja) 1997-01-08 1997-01-08 カラーレーザプリンタ

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US6031629A true US6031629A (en) 2000-02-29

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US (1) US6031629A (de)
EP (1) EP0855832B1 (de)
JP (1) JP3580063B2 (de)
DE (1) DE69813330T2 (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030001810A1 (en) * 2001-06-29 2003-01-02 Hisashi Yamaguchi Method for driving liquid crystal display, liquid crystal display device and monitor provided with the same
US6516175B2 (en) * 2001-07-03 2003-02-04 Toshiba Tec Kabushiki Kaisha Color image forming apparatus and developing method for color image forming apparatus
US20050248789A1 (en) * 2004-05-07 2005-11-10 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US20050260004A1 (en) * 2004-05-07 2005-11-24 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US20060244979A1 (en) * 2005-04-28 2006-11-02 Xerox Corporation Systems and methods for setting configuring rendering parameters for high-speed rendering devices
US20070209541A1 (en) * 2006-03-02 2007-09-13 Dainippon Screen Mfg.Co.,Ltd. Stability display method and stability display apparatus
US7310159B1 (en) * 1999-11-08 2007-12-18 Fujifilm Corporation Image outputting system
US20080107432A1 (en) * 2000-03-06 2008-05-08 Canon Kabushiki Kaisha Image forming apparatus and image forming method
US20080145073A1 (en) * 2006-12-13 2008-06-19 David Keith Lane Black Print Quality Enhancement for High Humidity Environment
US20110217052A1 (en) * 2010-03-05 2011-09-08 Canon Kabushiki Kaisha Color image forming apparatus having function of obtaining color information of patch

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6585340B1 (en) 1998-09-03 2003-07-01 Hewlett-Packard Development Company, L.P. Environmental and operational color calibration, with integrated ink limiting, in incremental printing
KR20120019728A (ko) * 2010-08-26 2012-03-07 엘지전자 주식회사 영상표시장치 및 그 동작방법

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0325395A2 (de) * 1988-01-19 1989-07-26 Canon Kabushiki Kaisha Abbildungsgerät für Farbbilder
EP0370482A1 (de) * 1988-11-25 1990-05-30 Ishihara Sangyo Kaisha, Ltd. Elektrophotographisches Farbverfahren
US5109275A (en) * 1989-12-29 1992-04-28 Matsushita Electric Industrial Co., Ltd. Printing signal correction and printer operation control apparatus utilizing neural network
EP0582997A1 (de) * 1992-08-10 1994-02-16 Sharp Kabushiki Kaisha Drucker

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0325395A2 (de) * 1988-01-19 1989-07-26 Canon Kabushiki Kaisha Abbildungsgerät für Farbbilder
EP0370482A1 (de) * 1988-11-25 1990-05-30 Ishihara Sangyo Kaisha, Ltd. Elektrophotographisches Farbverfahren
US5109275A (en) * 1989-12-29 1992-04-28 Matsushita Electric Industrial Co., Ltd. Printing signal correction and printer operation control apparatus utilizing neural network
EP0582997A1 (de) * 1992-08-10 1994-02-16 Sharp Kabushiki Kaisha Drucker

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7310159B1 (en) * 1999-11-08 2007-12-18 Fujifilm Corporation Image outputting system
US7499660B2 (en) * 2000-03-06 2009-03-03 Canon Kabushiki Kaisha Image forming apparatus and image forming method
US20080107432A1 (en) * 2000-03-06 2008-05-08 Canon Kabushiki Kaisha Image forming apparatus and image forming method
US6987499B2 (en) * 2001-06-29 2006-01-17 Nec Lcd Technologies, Ltd. Method for driving liquid crystal display, liquid crystal display device and monitor provided with the same
US20030001810A1 (en) * 2001-06-29 2003-01-02 Hisashi Yamaguchi Method for driving liquid crystal display, liquid crystal display device and monitor provided with the same
US6516175B2 (en) * 2001-07-03 2003-02-04 Toshiba Tec Kabushiki Kaisha Color image forming apparatus and developing method for color image forming apparatus
US6650859B2 (en) 2001-07-03 2003-11-18 Kabushiki Kaisha Toshiba Color image forming apparatus having a plurality of developing units
US7982908B2 (en) 2004-05-07 2011-07-19 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US20050248789A1 (en) * 2004-05-07 2005-11-10 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US20050260004A1 (en) * 2004-05-07 2005-11-24 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US8059318B2 (en) 2004-05-07 2011-11-15 Canon Kabushiki Kaisha Color image forming apparatus and control method therefor
US20060244979A1 (en) * 2005-04-28 2006-11-02 Xerox Corporation Systems and methods for setting configuring rendering parameters for high-speed rendering devices
US7852510B2 (en) 2005-04-28 2010-12-14 Xerox Corporation Systems and methods for setting configuring rendering parameters for high-speed rendering devices
US20070209541A1 (en) * 2006-03-02 2007-09-13 Dainippon Screen Mfg.Co.,Ltd. Stability display method and stability display apparatus
US7496302B2 (en) * 2006-12-13 2009-02-24 Lexmark International, Inc Black print quality enhancement for high humidity environment
US20080145073A1 (en) * 2006-12-13 2008-06-19 David Keith Lane Black Print Quality Enhancement for High Humidity Environment
US9075330B2 (en) 2010-03-05 2015-07-07 Canon Kabushiki Kaisha Color image forming apparatus having function of obtaining color information of patch
US20110217052A1 (en) * 2010-03-05 2011-09-08 Canon Kabushiki Kaisha Color image forming apparatus having function of obtaining color information of patch
US8594517B2 (en) * 2010-03-05 2013-11-26 Canon Kabushiki Kaisha Color image forming apparatus having function of obtaining color information of patch

Also Published As

Publication number Publication date
EP0855832A1 (de) 1998-07-29
DE69813330T2 (de) 2003-12-11
JPH10193688A (ja) 1998-07-28
DE69813330D1 (de) 2003-05-22
EP0855832B1 (de) 2003-04-16
JP3580063B2 (ja) 2004-10-20

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